Internal combustion engine



April 9, 1935. J. A. MOULD INTERNAL COMBUSTIQN ENGINE Filed July 1l, 1931 V9 7N v C@ Z Patented Apr. 9, 193s 1,997,071'.

UNITED STATES PATENT oFFiCE INTERNAL COMBUSTION ENGINE James A. Mould, Milwaukee, Wis., assigner to Gas Tool Patents Corporation, Chicago, Ill., a corporation o! Delaware Application 11, 1931, SerlalANo. 550,187

Claims. (Cl. 123-7) 'I'his invention relates to improvements in inwith packing rings to make gas tight the portion ternal combustion engines. It has particular refof the cylinder below piston 5. A relatively heavy erence to two cycle engines and to an internal spring I1 is seated on the anvil and supports a combustion hammer construction, although there relatively lighter Spring I8 SurrOU-nding hammer 5 are features subject to wide application. I9 carried by piston 5 and cseating against the 5 The object of the invention is to provide a pispiston proper. ton which will function 'satisfactorily in an in- While it may be possible to use a single spring ternal combustion hammer. With this object in for the support of the piston, the requirements as view it is desirable to produce a piston of light to temper and size of wire would be even more 10 weight because a piston relatively light as comexacting where a single spring is used than is 10 pared with the total weight of the tool will actuthe case where two springs are employed. The ally deliver a harder blow than a heavier piston. piston springs .aretreated more fully in a com- Furthermore it is desirable to minimize heat con- -panion application. Itis sufficient to state here duction to the piston for the protection of the that they must be exceptionally hard. 4Spring I8 supporting spring and the parts therebeneath in in and of itself is adequate for the support and l5 the tool and to preserve the nlm of lubricant bereturn of the piston while spring I1 provides not tween the piston and the cylinder. Accordingly merely a resilient and shock absorbing mounting the piston is preferably provided with internal but also, by reaSOn 0f its Preferably increased cavities certain of which may be made to produce StiineSS. iS Capable 0f maintaining the ,Spring an additional cooling effect by serving as transfer load on spring I8 notwithstanding a slight set 20 passages for conducting to the combustion chamwhich spring I8 takes when the tool is first put ber the mixture of gases compressed beneath the into use. piston. By sub-dividing the cavities into a num- The anvil I6 is s'ocketed to receive tle end of ber of passages of comparatively small cross sectool 20 which is retained in member 2I. The tion the cooling eiect of the gases is multiplied, anvil guide l5, tOOl retaining member 2| and ring 25 the heat conductivity of the of the piston is re- II are preferably made of steel held in clamping duced and the passages tend to intercept broken engagement upOn the cast iron cylinder casting pieces of piston springs and thus to prevent bro- 4 by means of tension rods 22, in accordance with ken springs from reaching the combustion chamthe disclosurel of my co-pending application ber.. aforesaid. l 30 Inthe drawing: For ignition timing the piston 5 is longitudi- Figure 1 is a Vertical axial section through a nally grooved at 23, the groove being provided two cycle gasoline engine embodying this invenwith a cam nose 24. A cam follower 25 rides in tion as it appears incorporated in a two cycle the groove and is acted upon by nose 24 to actuate combustion hammer. its moving contact 26 into engagement with a 35 Figure 2 is 'a transverse section taken in the spring supported contact 21 thereby 'closing the plane indicated at 2-2 in Figure 1. ignition circuit.

Like parts are identified by the same reference The anvil guide member I5 is provided with characters throughout the several views. bolts 29 mounting fuel tank 30 which carries a 40 In accordance with disclosure of my co-pending carburetor 3 I, the detailed construction of which 40 application entitled Internal combustion ham- Is immaterial to the present invention. The mer filed July 11, 1931, Serial No. 550,188, the charge is admitted to the sub-piston compression cylinder casting 4 is integral tln'oughout the path space in cylinder 4 through a port 32 in the anvil of movement of the piston 5 and may include guide member I5 and thence upwardly through integrally a jacket 6 provided with radiating fins the anvil guide member into the lower end of the 45 1. The cylinder casting includes integrally a cylinder casting. head portion 8 into which a spark plug 9 of con- In accordance with usual two cycle engine prac ventional designl has access. A shouldered extice the charge is first compressed below the plstension I0 of the cylinder casting receives a ring tonand at or near the end of the expansion stroke- II to which handles I2 are attached. of the piston a port is uncovered by the pistomto 60 v The lower end of the cylindercasting is, in the transfer the charge into the working cylinder. present device, not provided with any crank caser Whereas ordinarily the transfer passage is wholly but instead is closed by an anvil' guide-member formed Iwlthinyth'e cylinder and is fully exposed I5 in which the anvil I6 has a limited reciprocatto gas` compressed beneath the piston during the ing movement. The anvil is preferably provided expansion stroke, in the present device the only 55 ltion of recess 33.

portion of the transfer passage which is formed Within the cylinder casting is a recess at 33. The rest of the transfer passage is within the piston itself and comprises one or more vertical ducts 34 extending upwardly through the piston along the side remote from recess 33 and communicating with horizontal ducts 35 leading in the direc- 'I'he usev of a plurality of ducts is preferred because it gives mass and strength to the piston in a cellularconstruction which minimizes heat conductivity while at the same time giving a very substantial area of transfer passage.

The arrangement shown not only reduces heat conduction through the piston but also has a defi- -nite cooling effect on the piston attributable to the passage therethrough of the combustible mixture. A portion of the fuel used in carbureting the air of the mixture is vaporized and this has a definite cooling effect on the charge. The further vaporization of additional Aquantities. of fuel upon contact with hot surfaces of the piston results infurther absorption of heat therefrom. In an internal combustion hammer it is very important to limit heat transfer through the piston to preserve lubrication, to protect the spring and to avoid excessive heating of the liquid fuel in tank 30.

The cylinder wall recess 33 is completely closed by the piston in the compression position thereof. Its extent is barely suflicient to maintain communication across the piston head between ducts 35 and the firing chamber. Obviously gas compressed in the sub-piston portion of the cylinder is not even admitted to recess 33 until ducts 35 register therewith and is not admitted to the firing chamber until the piston head clears recess 33.

The foregoing disclosure will also make it apparent that, if the passages 35 were not provided,

Vheat would be more readily conducted from the piston head to the socket connection. Consequently, the passages not only limit the heat conducting area but also increase the heat radiating area.

The fact that thel gas transfer passages through the piston are subdivided to small cross section minimizes the possibility of a spring fragment reaching the combuston chamber where it would score the cylinder walls.

I claim: l

1. In an engine the combination with a cylinder having a combustion chamber anda sub-piston compression space, of a piston reciprocable in the cylinder and provided with a transfer passage leading toward the head of the piston and thence across the piston beneath the head, said cylinder having transfer passage means disposed to provide communication in the course of piston reciprocation between the piston passage and the combustion chamber, said passages limiting the heat conducting area and increasingA the heat radiating area.

2. In an engine the combination with a cylinder having a transfer recess in its wall, of a piston having in closer proximity to its head than the axial extent of said recess a plurality of transversev ducts extending through the piston and thence opening axially to the end of the piston remote from its head, said passages limiting the heat Vconducting area and increasing the heat radiating area.

3. In an internal combustion engine a piston provided beneath its head with a plurality of transverse bores crossing the piston from one side thereof and thence opening to the end of the piston remote from its head adjacent the other side thereof, said passages limiting the heat conducting area and increasing the heat radiating area.

4. An internal combustion hammer piston provided beneathA its head with a plurality of transverse bores crossing the piston from one side thereof, said piston having axially disposed passages adjacent one side and communicating with said transverse bores.

5. In an internal combustion, engine, the combination with a cylinder having a recessed wall, of a hammer piston reciprocal in the cylinder and provided with a plurality of transverse passages registrable with the recess and extending across the piston beneath its head to points adjacent the other side of the piston, said piston having axially disposed passages communicating withl the transverse passages and positioned in the side of the piston remote from said recess.

JAIMES MOULD. 

